Re: Soils

Stephen.Pushak at saudan_HAC.COM wrote Mar. 26:


>To anyone wishing to try out soil substrates and not wishing to get
>into the technical aspects, you should stick with the Jim Kelly
>recipe (email me if you don't get TAG) or others described in TAG
>which have been field tested. A potential problem with a lot of
>soil in a substrate is you might have too much growth!! :-0
>I'm curious to hear Paul Krombholz's comments when he gets time.
>I think he uses a higher ratio of soil and no solid fertilizer and
>no vermiculite but I haven't found his recipe in my saved files.
>He has said 1/3 manure & 2/3 soil composted aerobically for a
>few weeks but I don't know if that's mixed with gravel in the
>aquarium. Possibly he puts that in the bottom with a layer of
>gravel on top. I suspect 1/3 manure may be above the optimal
>organic content but apparently such substrates are possible with
>no harm to fishes or plants. Paul told of a story of a aquarist
>using 1/3 raw sheep manure, 1/3 raw bovine manure and 1/3 soil.
>An echinodorus plant flourished for several months before it
>turned anaerobic.

I have settled on two recipes.  For Crypts and other plants which I suspect
like a 'rich substrate', I use a 50:50 dried cow manure to topsoil mix.
The mix is composted aerobically in a sweater box or other covered
container for two to four weeks.  The cover should  not be air tight, but
should allow some air exchange.  In aquariums, I have covered the composted
mix with about 1/2 inch of gravel, or have used it straight.  It doesn't
seem to matter to the plants.  I put some egg shell in the mix that I grind
up with a morter and pestle into pieces that are small enough to pass
through a rice strainer. If you don't have a rice strainer, you can use
window screening, which has the same size mesh.  If you don't have a morter
and pestle, you can put the egg shells in a blender with water.  If you
don't have a blender, just mash up the shells with your fingers and don't
worry about getting pieces small enough to go through screening.  I put in
the eggshell because I figure that snail shells are a part of many aquatic
substrates.  I did a test once that showed that Hygrophila polysperma grew
better with the eggshells than without. (It still did pretty well without)
No, I havn't done that test with crypts.  They do quite well with the
eggshells, however.  A lot of other plants seem to grow well in the
composted manure-soil mix.

The story I refered to is: Marquis, Thomas E., HERE'S MUD IN YOUR TANK:
Part 1 TAG 4:6, 177-183, Nov/Dec.1991. (I copied this reference from the
index of The Aquatic Gardener on the Aquatic Gardeners Association home
page at http://blake.oit.unc.edu/~fish/aga/tag.html). (plug for AGA!!)   As
I recall, he used 2/3 FRESH manure and 1/3 soil without any composting
before putting it underwater and planting plants on it.  Also, as I recall,
his sword plant did very well for over 6 months and it may even have been
almost a year before it went downhill and the substrate started producing
bubbles. To me this is a great testimonial for the ability of swords to get
oxygen to their roots in spite of a soil that must have had a much greater
biological oxygen demand than any soil mix I would want to use.

The other recipe I use is 'soil soup'  For this I take any topsoil and mix
water gradually with much kneading.  At one point it gets like pie dough.
As I add more water it becomes like pudding.  I continue to add water until
it is like thick soup.  I pass this through a rice strainer and put about
1/4 to 1/2 inch in the bottom of the aquarium or plant tray.  Usually I mix
in some ground up egg shell.  Then I add an inch or so of gravel.  This
recipe is for plants that I suspect don't like a lot of organic matter in
their soil.  I know this is true for lace plants and some of the other
Aponogetons and Anubias.  Crypts seem to do all right in this mixtrure,
but, after 5 or 6 months of growth, they benefit from soluble iron
additions.  With this recipe you can get as low on the organic matter as
you want.  If you want very little organic matter, make your soil soup out
of subsoil, the lighter-colored, (usually) soil under the topsoil.

I have been reading the discussion Stephen Pushak started about soils, but
havn't had the time to contribute until now.  One thing I am seeing is a
lot of sentiment for keeping sulfate as low as possible to prevent hydrogen
sulphide formation.  I don't think we have to worry about this.  Plants do
need sulfur as a macro (not micro!) nutrient, and the the sulfate ion is
their usual uptake form. We could be getting sulfur deficient plants if we
try too hard to keep sulfur low.   As dr. Dave said, you don't get H2S as
long as there is iron available to precipitate out the sulfide ion as FeS
(iron sulfide).  Besides, the plants aerate the soil with their roots.  How
many readers of this list have had their plants or fish killed where you
knew that hydrogen sulfide was the culprit.  I have had a tank go anaerobic
on me due to criminal neglect, but what killed the plants was lack of
oxygen, I am pretty sure.  The water became anaerobic, as well as the soil.

Iron sulfide forms a very characteristic black precipitate, and I have only
very rarely seen this form at the substrate surface in an aquarium with
soil or soil under gravel.  Even when I did see this, the plants didn't
seem to be bothered.

Gotta go!

Paul Krombholz                  Tougaloo College, Tougaloo, MS  39174

Where I am wondering what happened to my spring break!